This invention relates to the turning of the bushings of a track of a track-type vehicle, and more particularly, to such turning of bushings with a track in a fully assembled state on the vehicle.
Commonly used track chains for earthmoving vehicles comprise a plurality of track links. The track links are connected into two parallel endless chains by means of track link hinge joints having track pins joining the ends of adjacent pairs of links and spanning the space between the parallel chains. Drive sprockets drive the track chains and provide locomotion for the vehicle by acting against bushings upon the track pins.
For efficient and low cost operation, it is, of course, desirable to construct a track chain in a manner to provide for a long, trouble-free operating life. All track parts are subject to a high rate of wear because of the service they perform and the environment in which they operate. Recent developments in seals and lubrication methods promise to increase the life of some track parts measurably and it appears that the track pin bushing in its present form may well continue to be the first element of the track to require maintenance.
Force for driving the tracks by sprocket is received upon a given portion of the bushing. Additionally, as each bushing comes into engagement with or tends to be disengaged from the sprocket, there is relative pivotal motion between the two adjacent links. Since the bushing is conventionally secured to one of these links, it is caused to rotate while in engagement with the sprocket. The rotation of the bushing against the sprocket is commonly referred to as "scrubbing" and causes substantial abrasion of the bushing.
U.S. Pat. No. 3,915,036, issued Oct. 28, 1975 in the name of Vanlandingham et al (assigned to the assignee of this invention) discloses apparatus for rotating the bushings of an assembled track in place on a tractor to present new bushing wear areas to the sprocket which engages these bushings. With such apparatus, rotative torgue is applied to a clamp member in engagement with a bushing, to so rotate the bushing.
While such a system is highly effective for so turning such bushings, it will be understood that an increase in efficiency thereof, including a reduction in the time and force necessary to so turn such bushings, through the more efficient use of rotational force applied thereto, is highly desirable.